cassette player. How it works

[david90]

is the signal coming out of the HEAD a soundwave or is there another stage where it is converted to sound?

Why is it necessary to preamp a signal first before it is power amp?

 

[dunn]

"is the signal coming out of the HEAD a soundwave or is there another stage where it is converted to sound? "

I think think that it comes out of the same output as the speakers but it is attenuated.

Also some equipment use the BA3612AKV chip for this purpose.

Check out the data sheet at:
**broken link removed**
(or see attachment.)


"Why is it necessary to preamp a signal first before it is power amp?"

The preamp routes the chosen signal to the power amp. stage, which then boosts it into the audible range and sends it, via wire, to the speakers.

How does it do this? (I hear you ask.)

Well, see all those buttons on the front of the radio, right? These are actually part of the preamplifier section. When you press the FM button, the circuitry inside the preamp directs the signal from the tuner, through the preamp, to the power amplifier. Likewise for the CD player and the cassette. The preamp stage also includes all the tone controls (bass, treble, etc.), sound processing (balance, fade and the like), and other signal processing circuits. For instance, some vehicles, such as Chrysler, offer a three-, five-, or seven-band equalizer built into the head unit. In this case, the equalizer is actually an expanded tone control. The signal is fed through the equalizer in a loop, exiting out of the preamplifier and returning back to it with the signal altered per your adjustments. The preamp then sends the altered signal onto the amplifier. All the other controls typically operate in a similar "loop" scenario.

If you have any steering wheel-mounted controls, these are also usually directed through the preamp section.

 

[echo47]

A quick Google search found this short description:
http://www.bcae1.com/tapehead.htm

 

[david90]

great info. I'd like to diy a steering control for my stock radio that doesn't come with one.

Any idea on how to hack into the preamp stage to control the volume?